A poop ninja is one that silently poops their pants in the presence of others.

An alternate version according to www.poopninjas.com is a pooper scooper trained in the arts of the ninja.
Ex. 1 A poop ninja needs to go to the bathroom but thinks they can hold it. They accidently let some slip out in their pants, but keep a straight face. Their mood and mannerisms do not change, and no one can tell any difference.

Ex 2. A poop ninja stealthily cleans a yard full of dog poop.
by pooppooper March 10, 2011
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When one takes an accidental shit in their pants, and then blaming it on a fictional character, sometimes refered to as just "someone", or the "Poop Ninja"

Can be used as a verb, as well as a noun, sometimes even both.
Example 1: Someone took a shit in my pants, I don't know who, and I don't know why, but this is an issue that needs to be addressed immediately

Example 2:
Jimmy to Ricky: Dammit! Look out man, The Poop Ninja is on the loose. He got me.
by Big_Mac October 26, 2010
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A two person game in which one person lies on their back with pants either off or around their ankles, shooting projectile turds from their anus at player two, whom of which has a sword in hand in the hopes of cutting the projectile turds out of the air a la fruit ninja.
Jim: Hey Sarah, want to play a rousing game of poop ninja?
Sarah: Sure Jim! Just give me 25 minutes to finish digesting my lunch.
by Tommy dugan June 14, 2023
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